Metal complexes of azo-dyestuffs. Part III. Cobalt complexes of o-hydroxydiarylazo-compounds

Cobalt chloride reacts with 1-phenylazo-2-naphthol in ethanol to form a novel complex which is shown to be dichloro-bis-(1-phenylazo-2-naphthol)cobalt(II). The latter is also formed when bis-(1-phenylazo-2-naphtholato)cobalt(II) reacts with 2 mol. of hydrogen chloride. o-Hydroxydiarylazo-compounds react with cobalt acetate to give neutral cobalt(II) complexes having 2 : 1 stoicheiometry and tetrahedral geometry, and with sodium tris(carbonato)cobaltate(III) to form neutral cobalt(III) complexes having 3 : 1 stoicheiometry. The interconversion of a number of the complexes is described and they are compared with cobalt complexes of N-arylsalicylideneimines.